It was Schememann who first taught me that liturgical acts are themselves means (media) that bring us to heaven. The consequence is that worship can never be mere personal preference or trend or fad. With the liturgy uniting for a moment of preview heaven and earth in the Word that ushers in that future and the Sacrament that is the foretaste of it, liturgy cannot be adiaphora or anything indifferent. The medium of the liturgy is not simply a neutral form on which we hang what it is we desire but is itself both confession and proclamation. Its power is that speaking within the Divine Service is the Word that does what it promises and the Sacrament that enacts what it symbolizes.
One of the great fallacies of the modern liturgical movement is that it focused too much in liturgical form and architectural style the present moment -- the horizontal dimension. With that focus, the real power and gift of the liturgy is lost. For it is not simply an earthly community that is established but a heavenly communion into which we are entered by God's grace and favor. Even where Latin became the vernacular and hymns entered into the service, the earlier liturgies never lost their focus on that which was beyond but accessible because Christ was present in His Word and Sacrament. This immediacy of His presence was not the end but itself pointed to the outcome and goal of our salvation -- the perfect communion and reunion with God and the saints, angels and archangels, around His throne forever.
One of the great foibles of Lutheranism is the idea that we worship the way we do because it is traditional (we have a hymnal and that is what we use) and that it is possible to retain the content while not using the form. We must recover why the hymnal and its liturgy (and the ceremonial that attends it) are important to the confession and profession of the faith. We must dig deeper than the tradition of the last 50 or 100 or even 175 years in order to understand, recover, and restore our claim to be catholic in content and practice. Melancthon understood this when the Augsburg Confession was written but we seem to have forgotten or no longer care that catholicity is our claim. Worshiping like Lutherans means little if anything and everything can define what that worship is. The only worshiping like Lutherans that means something is that which is consistent with and gives outward form to what we confess in our Symbols.
By the way, adiaphora has become the rabbit hole into which every heresy, fallacy, and apostasy hides. What was meant as a way out of the rigid central control of Rome has become the license to do whatever pastors and parishes please and with it the right to call that oddness Lutheran. To be quite frank, I am over it. Adiaphora had meaning when there was integrity to what happened on Sunday morning but given that the majority of LCMS folk worship in congregations that have contemporary worship as at least an option violates whatever usefulness the term once had.
Lastly, the fear was that the liturgical movement would make every denomination look the same on Sunday morning. What has accomplished this far more effectively is evangelical style contemporary worship. It seems the whole of Protestantism has given into an entertainment style service in which technology has become one of the primary sacraments and relevance and likes the indicators of success. Lutherans should beware but some Lutherans have decided that there is no future for a Lutheranism of the Divine Service and the sturdy hymns of old. They have cast their lot not with the Church of the Lutheran Confessions but with a media savvy church where God's job is to make us feel better, achieve our dreams, and preserve every false illusion about life, sin, and death.